The present invention relates to perovskite-related materials and methods to make a perovskite-related structure, as well as to methods of making ternary oxide dielectric films and capacitors and other devices containing the films.
Dielectric films or layers are used in a variety of applications, such as anode production and capacitors. Typically, dielectric films comprised of binary metal oxides, such as Ta2O5 and Nb2O5, are formed on a metal substrate creating a metal-metal oxide interface. However, when using binary metal oxides, such as Ta2O5 and Nb2O5, the binary metal oxide can break down to form undesirable metal oxides, such as NbO2, which can then diffuse across the interface into the metal anode, for instance. This is especially true in the case of Nb2O5, because the interface involving niobium is particularly sensitive to time and temperature. Moreover, the method for making the binary metal oxides generally involves several steps, which increases production costs.
Conventional binary metal oxide films have several disadvantages. First, a thermodynamic instability can exist between the substrate and the binary oxide dielectric interface, which often results in the formation of intermediate oxides. As a result of intermediate oxide formation, oxygen vacancies promote oxide-ion migration, which can affect the critical performance characteristics of the host device. For example, in capacitors, oxygen-ion vacancies facilitate space-charge polarization, dielectric loss, and low breakdown voltage. The above conditions are characteristic of a non-uniform, non-coherent, and/or non-mechanically sound dielectric film. Second, surface films of binary metal oxides often degrade, which affect the performance of devices into which the films are incorporated. Furthermore, high-temperature (e.g., above about 300° C.) processing typically used in formation of binary metal oxide films enhances oxide mobility and favors comproportionation even at a comparatively stable Ta/Ta2O5 interface. Both the reaction product and the enhanced oxygen mobility promote space charge polarization and dielectric loss.
With an ever-increasing demand for producing, at low cost, a dielectric film having a high thermodynamic stability of the substrate/dielectric interface, it is an important priority to provide a one-step perovskite-related ternary oxide film. Accordingly, a need exists to overcome one or more of the above-described disadvantages of conventional dielectric films.